Influence du statut hydrique sur la variation des paramètres physiologiques et biomécaniques lors d'un exercice de pédalage de longue durée

Purpose. – Study was to investigate the influence of hydration status on maximal and sub-maximal muscular performances during prolonged cycling exercise.Methods. – Eight well-trained subjects exercised for 180 min in a moderate environment at a workload requiring ∼60% maximal oxygen uptake. Two conditions, with fluid (F) and no fluid ingestion (SF), were investigated. During all the tests oxygen uptake was collected, cadence and applied force on the cranks were recorded. Furthermore maximal voluntary contraction performance (MVC) was recorded before and immediately after exercise.Results. – A significant increase in energy cost of cycling was observed during the no fluid condition only. After exercise a significant reduction in MVC was recorded whatever the condition. No significant change in cycling mechanics was observed.Conclusion. – This study indicate that cycling during 3 h leads to a significant impairment of maximal muscular performance but has no effect in cycling mechanics in well trained cyclists. Furthermore this effect seems independent from hydration status.     

Influence de la distance de course sur les paramètres cinématiques de nage chez les nageurs avec palmes de haut niveau

Introduction – Finswimming is a new sport activity. The optimization of the leg’s propulsive action is fundamental to improve the performance. The aim of this work is to quantify finswimmer’s movements per race distances, using a kinematic analysis.Fact synthesis – Five elite finswimmers were video recorded during underwater races. The connections between the average velocity of stroke, frequency and range of finswimmers undulation are observed as a fonction of race distance.Conclusion – Finswimmers are shown to adjust and to stabilize instantaneously their movements in terms of race distance.     

Pratique sportive et conduite dopante d'un échantillon représentatif des élèves de Midi-Pyrénées

Objective – Estimate the phenomenon of doping in sport among french adolescents.Method – Our effective population was the students of the Midi-Pyrenees French Region in 1999 exception made of the high-level sport section. The data were gathered by an anonymous questionnaire filled by a representative sample of 1 506 girls and 1 420 boys aged from 13 to 20 randomly selected by a two stage sampling. Regionals estimations are given.Results – A sport-practice out of school concerned 85% of our sample. Nearly 3 000 students of our effective population (2% of this population) would consume a substance classified as a doping-drug for sport (sometimes innocently), and 8.6% of our athletes would consider to know a « friend consumming doping substances for sport-practice». The situation would be more worrying if we consider that more than 12 000 adolescents (8.7%) of the effective population would be tempted to consum suc a substance. The most cited doping substances were caffeine shape of tablet, beta 2 mimetics and cannabis. A total of nine students also declared a creatine consumption.     

Facteurs mécaniques de la performance en sprint sur 100 m chez des athlètes entraînés

Aims. – Study mechanical muscular parameters linked with performance in the different parts of a 100 m intrained athletes.Methods and results. – Force, velocity and muscular power of ten sprinters as well as their stiffness were correlated to their performances on a 100 m sprint. Maximal forces and velocities, jump height and muscular power of athletes were significantly correlated (p < 0,05) respectively with mean 20, 40 and 60 m velocities and with the time to reach maximal velocity. No other mechanical muscular parameter assessed was linked with performance in the maximal velocity phase or in the end of the 100 m.Conclusions. – Muscular power (and its components of force and velocity), is a determining factor of the performance in the acceleration phase. Key factors explaining performance in the following phases remaining unexplained.     

Mise en évidence de la sollicitation du cycle des purines nucléotides lors d’un combat de judo

Objective. – Energy solicitation during a judo match and the kinetics of recovery were assessed by measuring the metabolites of oxypurine cascade level and the glycolytic pathway.Methods. – Venous blood samples were taken from sixteen national judo athletes (aged 18.4 ± 1.6 years), before (T1) and at 3 minutes (T2), 1 hour (T3) and 24 hours (T4) post-match. A 7-day diet record was used to evaluate the values for nutrient intakes.Results. – Nutrient analysis indicated that these athletes followed a low carbohydrate diet. Plasma lactate concentration rose to 12.3 ± 1.8 mmol l^–1 at the end of the match. An increase in extracellular markers of muscle adenine nucleotide catabolism, urea and creatinine levels was observed at T2 while uric acid levels remained unchanged. Persistent high concentrations of urea were observed during the post-training recovery period for 24 h. Ammonia, hypoxanthine, xanthine and creatinine values returned to their control levels within 12 h of recovery. Uric acid concentrations rose from T3 and did not return to baseline 24 h after the match.Conclusions. – These results showed that a judo match induces mobilisation of protein metabolism.     

Dissociation de la réponse du système adrénergique à l'exercice après un repas hyperglucidique et ses conséquences sur la mobilisation des lipides

Aims – Evaluate hyperglucidic meal effect on changes of catecholamines concentrations and on lipids mobilization during exercise.Methods and results – During exercise (one hour at 50% of VO_2max), the adrenaline concentrations increased twice more in fed men than in fast men, whereas no difference was shown for noradrenaline. The exercise-induced increase in lipolysis was similar whatever the nutritional state of subjects (fed or fasted).Conclusion – In fed men, important increase of adrenaline concentrations during exercise counteracted antilipolytic effect of insulin wich occured after ingestion of hyperglucidic meal.